Gideon's Revenge
by waffleman1314-AJ ThaPlatypus
Summary: The sequel to The Mysterious Dimension is here! Gideon finds a way to travel across dimensions without Doofenshmirtz's inators. He plans to exact his revenge on all, but the Pines twins gang up with Phineas, Ferb, and Perry once more to make sure Gideon's plan fails.
1. Mabel Melancholia

**There was a call for The Mysterious Dimension to have it's sequel, so here it begins! This was a prospective story for some time, but the demand for part two has pushed it into reality! Here is chapter one of the sequel! -AJ ThaPlatypus**

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The front door of the Mystery Shack swung open and slammed up against the wall with a loud bang. I instantly dropped the broom in my hand and looked its way. A sopping wet Grunkle Stan was standing in the threshold with a furious expression painted across his face. Swallowing hard, I stooped down and picked the broom back up. I gave my twin sister Mabel, who was cleaning one of the windows, a nervous glance. She rolled her eyes and continued to clean.

"Gideon Gleeful has gotten on my last nerve," Stan grumbled. He slammed the door closed behind himself and stomped over to where I was standing. "Where the heck is Soos?"

"Lunch break," I mustered.

"He's got five minutes and then I'm getting uglier," Stan growled. He turned to look at Mabel. "Why is no one working the register? Where's Wendy?!"

"She's on vacation with her parents," I told him. Why couldn't Mabel do the talking? She was usually full of comments. I readjusted my grip on the broom and tried to avoid Stan's gaze by busying myself with sweeping up a small area of the floor.

"Mabel, you take the register!" Stan barked. "Dipper, go find Soos!"

"I told you, he's on lunch break!" I said, trying to will myself to not get stressed with him. He narrowed his eyes at me. I dropped the broom and crossed my arms. "He'll be back in ten minutes."

"I said he needed to be back in _five_," Stan said, narrowing his eyes at me.

"Why don't you make Dipper work the register?" Mabel said gloomily. Stan gave her a hard look. She slowly made her way over to the counter and rested her elbows on it.

"What's with your attitudes today?" Stan raised an eyebrow.

"That's the first time I've heard her talk all day," I shrugged. Stan went to say something else, but I held up a hand and quickly left the shop to locate Soos. Heck if I knew where he went. He went out for lunch fifteen minutes prior to Stan's "delightful" entry. The only problem was…Soos had packed his lunch. He could be anywhere. Luckily for me, he wasn't too far.

I peeked around the corner of the Mystery Shack to find him sitting in the golf cart and sharing a bag of cold French fries with Gompers, the goat that one typically found outside of the Shack. Sighing, I sprinted over to him and tapped on the hood of the golf cart.

"Hey, dude, watch this!" Soos chuckled. He tossed a fry about ten feet away from the cart and stared at it. I blinked. Gompers inched his way over to the spot and started munching on it. "Neat trick, eh?"

"Um, sure," I nodded. "Look, Soos, Grunkle Stan wants you back in the Shack."

"I still got ten minutes," Soos pointed to his wrist.

"You're not wearing a watch," I told him. He looked at his wrist and hummed in thought. "But I know. Stan wants you in early. He's in a really bad mood. And apparently so is Mabel."

"That's not cool, dude," Soos frowned. He followed me back inside regardless. I sighed loudly and picked the broom back up. Grunkle Stan shot me a look.

This wasn't the first summer Mabel and I had spent with our Great Uncle Stan Pines in the weird town of Gravity Falls. In fact, it was our fourth. We'd been coming ever since we were twelve. The first year had been great, and certainly the most interesting- but helping out around Grunkle Stan's tourist trap scam, the Mystery Shack, has always been on our summer agenda.

The rest of the day dragged on like so. We did everything Grunkle Stan demanded of us. Dinner was quiet, save for Stan going on and on about his earlier confrontation with his business nemesis, Gideon Charles Gleeful.

Gideon. I needn't explain what he did to Grunkle Stan for you to know just how un-tasteful he is. Ever since I'd met the guy, I'd found him nothing less than an annoying villain. At first, I'd questioned how he could be Stan's archenemy on any grounds. A closer look at him proved he was a psychotic creep. He had a queer crush on my twin sister, was bent on getting revenge on my entire family, and got exceedingly angry about anything that plucked his nerves.

After dinner, I hurried upstairs to get ready for bed. I quickly changed into my night clothes before Mabel entered our room. She got into her night clothes without even looking at me. I picked up my toothbrush and shot her a look. She didn't turn to return it. I waited a few seconds before addressing her.

"Okay, what's the deal?" I demanded. "You've had one sentence all day. That's all. What's bothering you?"

"Nothing," Mabel growled. She brushed past me to grab her own toothbrush. My eyes focused on a calendar that was hanging on the wall behind her. I looked at the date and bit my lip. I knew I was going to regret asking the next question.

"This is about the other dimension, isn't it?" I managed. The toothbrush fell out of Mabel's hand and landed in the sink with a few clanks. She looked at me with a blank expression. I knew then that I'd struck a chord. "It is, isn't it? Hasn't four years taught you anything, Mabel? We're never going to see them again! Just forget about it. It was a pleasant memory and nothing more."

"You don't know that!" Mabel shot back. "Anything could happen!"

"Remember when we agreed to not cross dimensions again because it was too risky?" I countered. "Phineas and Ferb promised that they would destroy that inator thing so that Gideon and Dr. D couldn't cross dimensions again."

"You're such a naysayer, Dipper," Mabel frowned.

"You don't even know what naysayer means," I folded my arms.

"Well, whatever it is," Mabel scowled, "you are one."

She picked her toothbrush back up and reached for the toothpaste to apply it. I watched her for a moment, thinking of some way to convince her that dimension-travelling was forever out of the question. Mabel squeezed too much toothpaste onto her brush, wet it a little, and shoved it into her mouth. I took that moment to offer my rebuttal.

"If we even tried to cross dimensions again, Gideon would follow us," I furrowed my brow a little and grabbed for the toothpaste as well. Mabel shot me a look. "It's true, Mabel! He would follow us and try to do exactly what he tried to do before. Gideon certainly won't be forgiving us for thwarting him last time. What makes you think he's put that idea out of his mind?"

"It's been four years," Mabel shrugged. Toothpaste foam was all over her mouth. She rinsed off her toothbrush and spit in the sink. "Maybe he forgot."

"Gideon? Forget?" I blinked. I shook my head vigorously. "Not in a million years. He still hasn't forgotten about the time I helped you break up with him."

"I don't even remember that," Mabel grimaced. "Well…didn't."

"Exactly!" I said, grabbing the toothpaste. I squeezed a pea-sized drop onto my toothbrush and went to place it in my mouth. "My point is we can't risk trying to get back to Danville. We just have to accept the fact that it's over. They've probably even forgotten us by now."

Mabel appeared to consider this for a moment. The look on her face told me she hated the truth. But it was just that. We would never see them again. Never.

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**:) Part two is officially rolling!**


	2. Much-Desired Revenge

**Chapter Two! Let's get this ball rollin'! -AJ**

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It had taken Gideon a lot of headache to steal back his book from Dipper Pines. For four years, Dipper had kept a close eye on it. Every chance Gideon had had, every single time Gideon had been close, Dipper had conveniently been able to recover and keep the book in his care.

Not tonight.

Gideon had waited for the Pines twins to fall asleep and Stan to be preoccupied with watching "The Duchess Approves: The Sequel" before creeping upstairs to snatch the book from its place on Dipper's shelf. Soos- he was no obstacle. All Gideon had to do was use a laser pointer to distract the man-child and entry to the Pines household was accomplished.

He crept up the stairs gingerly and tip-toed down the hall. Giddiness rose in his soul as he approached the door to the Pines twins' bedroom. Success would be his in a matter of moments. He'd take the book, recite the words to open the portal, and be on his merry way to find the two villains again. Not that he needed those two insignificant men; he could take over three dimensions without their help. It didn't hurt to have a powerful ally and a stupid man who follows your every demand, though.

Revenge would soon be his. He wrapped his fingers around the doorknob and silently twisted it. Pushing the door open, he took a quick look to see if either twin was awake before entering the room. He stood in the threshold for a moment staring at Mabel in her sleep. Her silky brown hair…her sparkly personality…ah, yes, she was the perfect female in Gideon's mind. He shook his head. He had to focus.

His eyes darted over to a shelf by Dipper's bed. It wasn't hard to miss the book he was looking for. By luck, the other book was right beside it. He plucked each book off of its place on the shelf and set them down on the floor. Why wait to cross dimensions? The twins wouldn't be able to stop him at this point. He opened the first book to the page he needed and grinned evilly.

"The Pines family will finally suffer my wrath!" Gideon chuckled. He ran one finger along the instructions for opening a portal. To his excitement, nothing even had to be recited. He could do the entire thing in his head. But something wasn't right. The room was too silent. His eyes jerked up to see both Dipper and Mabel staring at him.

"Mabel…you stall, I'll call the cops," Dipper blinked. His sister nodded.

"Oh, no you don't, Dipper Pines," Gideon drew a deep breath. He started to mentally go over the incantation. If the book was right, he'd be transported before the Pines twins could do anything about it. "You're not stopping me this time."

"You keep thinking that," Dipper crossed his arms. He snatched his hat off of his side table and went to pick up a cellphone. His eyes darted back to Gideon's and narrowed. "Thinking…"

Gideon's heart rate picked up a little. If Dipper figured him out, he could easily do his best to distract him from his work. He focused even harder on the words. Any second now…any second the portal would open and he'd be gone. And the books along with him.

"Dipper, what are you doing!" Mabel cried.

It was more a statement than a question. Pulling his consciousness forward a little, Gideon was shocked to see Dipper Pines heading straight for him. Everything after happened too quickly. They collided. The world felt as if it were giving away around him, not just beneath his feet. Mabel screamed. Dipper shouted. Their voices didn't die out as the portal transported them to the next dimension. Gideon's head spun round and round as he lost all valid sensory input. He kept his eyes shut tight until everything was still again and he could feel the ground once more.

"I'm sorry," Mabel's voice said nonchalantly. "Are we interrupting you?"

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**I'm glad to be working with this story again ^_^**


	3. Four Years Later

**Chapter three is here! Yay! Much longer than the last so, hourah! -AJ**

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I opened my eyes to see Mabel gawking at a pair of people kissing. Well, more like frozen awkwardly in a kiss and staring at the three of us in confusion. What surprised me the most was that the guy in this couple was none other than Phineas Flynn- the boy we'd met in the other dimension four years ago. Before I could apologize for simply appearing, Gideon leapt up and squealed in delight.

"You might have tried to stop me, Dipper Pines, but I still accomplished crossing back into this dimension!" he said with an evil grin. He snatched up the books from underneath him and grasped Mabel by the hand. "Won't you come with me, my marshmallow?"

"Gideon, we've been over this, I'm not your marshmallow!" Mabel pulled away from him, but he was prepared with another solution. The insane boy opened his book right to the middle and faced it towards Mabel. Black, inky tendrils shot out of its pages and wrapped around my twin.

"Mabel!" I shouted. "Gideon, stop it!"

"Make me, Dipper Pines!" he cackled. I watched my sister get pulled into the book faster than I could shout her name a second time. Gideon slammed the book closed and smiled at me. "Like that, Dipper Pines? I learned it from a video game I saw once. Mabel is mine, now!"

Without another word, Gideon bolted off, with both books in hand. I sprinted after him. He turned the corner of a building. I followed, but was annoyed to find that he'd disappeared. My first thought was about how he'd done so. My second was that I wanted to destroy that little punk for stealing my sister. I felt a hand on my shoulder. Turning around, there stood Phineas.

It would be lying to say that four years hadn't changed him a bit. He was about a head taller than me, slightly thinner, and appeared to be attempting to work a goatee. Behind him was the girl he'd been kissing a moment ago. She had long, black hair, big blue eyes, and was wearing a short pink dress.

"I know your face…" he said slowly.

"Dipper," I told him. He blinked. "Dipper Pines. You guys crossed over into our dimension four years ago. Well, you, your brother, that pharmacist, and your little platypus friend. Remember?"

"DIPPER!" Phineas exclaimed. He scooped me into a hug and then shook my hand. "I can't believe you're back!"

"Neither can I," I admitted.

"So that freak must have been Gideon!" he concluded. "And the girl his book just swallowed was Mabel, oh, now I remember!"

"Yep," I sighed. I glanced at his girlfriend, who seemed nothing less than lost. "Who's this?"

"Oh, this is Isabella," Phineas told me. He pulled her close and waved at me. "Dipper, Isabella; Isabella, Dipper."

"Nice to meet you, Dipper," Isabella also shook my hand.

"Is there any way I can help you out, Dipper?" Phineas asked. "I mean, Gideon's got the books, he's got Mabel. I can easily go get Ferb and Candace to help."

"Yeah, let's get to your place, first," I told him. He nodded. "I'm taking that to mean Perry's off-duty?"

"What?" Phineas stifled a laugh. "Oh, no, he retired two years ago."  
"What for?" I blinked. Phineas waved me over to a bright red car and we got in. I took the back seat, since Isabella seemed to silently claim shotgun. Phineas started the car and began the drive to his house.

"Dipper, I hate to point out the obvious, but it's been four years since you've last seen Perry," Phineas chuckled. "He's old. We might have only aged a little bit, but four years has taken its toll on the poor guy."

"He's okay, though, right?" I frowned.

"Eh, depends on your definition of okay," Phineas shrugged. "He's not unhappy. But he is in a lot of pain. It's not my fault he hates taking his meds."

"Pain?" I swallowed.

"Chill, Dipper, it's nothing he can't handle," Phineas reassured me. "Just arthritis and occasional pains from old injuries. That, and he just recently fractured his knee tripping down the stairs."

"Ouch," I commented. Phineas pulled into his driveway and shut the car off. We got out and headed up to the front door. He pulled a key out of his pocket and unlocked the front door. "I thought you said your brother and sister were home?"

"They are," Phineas told me. "Candace just likes the doors locked."

"Uh…okay," I blinked. We walked inside, and the first thing I noticed was that something was burnt. Phineas and Isabella noticed it, too. We all rushed for the kitchen and saw Candace setting a pie on the floor. She stood up quickly and bit her lip.

"Um, Candace," Phineas crossed his arms. "Why are you baking pies?"

"Well, I was trying to help with Stacy's bake sale, but…" she looked down at the floor. We all looked down as well. Empty pie shells covered the floor- and when I say covered, I literally mean covered. They were all dirty, and crumbs surrounding them suggested that they'd been burnt.

"Hey, Candace…can you please pick a flavor _other_ than cherry?" a muffled voice from behind the counter grumbled. I leaned over to see Perry on the floor with his bill in the pie she'd just put on the floor. Phineas and Isabella sighed and leaned over as well. I noted a cast on his left back ankle. "The past eight have been cherry, seriously…"

"Oh, quiet, you!" Candace growled. "The next one's blueberry, but I'm hoping not to burn it, too."

"Whatever," came the mumbled reply. I was shocked that I could even understand it with his mouth full of pie.

"Can I ask just how many pies you've baked?" Phineas grimaced at Candace.

"I lost count after ten…" Perry replied for her.

"Count the pie pans, Phineas," Candace sighed. She turned to check on her next pie and frowned. I looked over to see Phineas counting the pans. Didn't he know that was sarcasm? I frowned and put my hands in my vest pockets.

"Where are you parents at?" I asked Candace, knowing that I wouldn't get Phineas out of his pie pan counting. "It's late."

"They're at an overnight conference for antiquities," she replied, turning back to us.

"Okay, grand total of twenty-nine," Phineas smiled. His smile was immediately replaced with a frown. "Perry, good grief! Show some self-control!"

"Hmm?" Perry hummed. We looked back down at the platypus to see him literally lying in the pie pan he'd just cleared, chewing on the last bit of pie. He swallowed and sighed, draping his front paws over the edge of the pan. "So, Dipper…how'd you get back in this dimension?"

"I'll explain that as soon as we find Ferb," I told him.

"Yeah, where is Ferb?" Phineas lifted an eyebrow.

"He's upstairs," Perry told us. The platypus stretched one leg out to pull himself out of the pan and frowned. "Okay…maybe not…"

"Come here, you lazy boy," Phineas laughed. He picked Perry up out of the pan and held him under the armpits. "Alright, everybody, upstairs we go!"

Phineas ran upstairs with Isabella trailing behind him. Sighing, I followed. Last time I'd been here, I hadn't been upstairs. They went into one of the bedrooms. Ferb was lying face-up on a purple-clad bed. He was holding a book open over his eyes. I read the cover; it was H.G. Well's _The Time Machine_.

"Hey, Ferb," Phineas smiled. "Guess who showed up literally out of nowhere?"

Ferb put the book down a little and looked up at me. He sat up. To me, he looked pretty much the same, only taller; much taller than Phineas. He ran one hand through his thick, green hair and stared at me like I was a ghost from the past. His stare felt a little eerie to me.

"Hi," I waved. Ferb raised his hand and put it back down.

"So, Dipper," Phineas said as he sat down on a yellow bed and set Perry down next to him. "Tell us exactly what's going on."

"Well, it happened really fast," I told them. "One minute, I was sleeping. The next, I'm wide awake, staring at Gideon. He's in the middle of me and Mabel's bedroom. The two books, mine and his, that I've kept from him for four years, were at his feet. He didn't say anything. Mabel and I figured out quickly that he was using some kind of mental trick and went to distract him. When we touched him, all three of us were sucked into a vortex and that's when we dropped in on you and Isabella making out."

"You two were making out?" Ferb interrupted, pointing a finger at Phineas and Isabella. They both blushed.

"Anyways, once we got here, Gideon used one book to trap Mabel and then he literally vanished," I continued.

"He trapped Mabel with a book?" Perry hummed. "I hate when that happens. You look in a book, and then someone slams it on you…not pleasant."

"Not that kind of trap," I shook my head. I'd never even considered what he was saying. "I mean, he opened the book and it looked like the ink literally reached out, wrapped itself around her, and pulled her into it!"

"Ooooooh," Phineas, Ferb, and Perry gasped in unison.

"That was freaky…" Isabella murmured.

"You're telling me," I blinked. "That was borderline twins-behavior. And trust me- I know twins."

"Sorry," Phineas chuckled. "So we've got Gideon on the loose in Danville with two of the books and Mabel. Any clues as to what his goal is at this point?"

"As of right now, it's safe to assume he's still on his tangent from last time," I said, putting my hands into my pockets again. "He's been trying to get his revenge on my family ever since I broke up with him for Mabel. And he's been trying to reclaim the books ever since he lost his during our last meeting. He's hard-pressed to forget anything."

"I see," Phineas hummed. "So if he's been trying to get into this dimension, and he's pretty much trying to do the same exact thing as he did last time, then wouldn't that mean we'd know where he was going?"

"Hopefully," I shrugged. "But it's been awhile…I don't remember the name of…"

"Doofenshmirtz," Perry filled in for me. "He's looking for my ex-nemesis."

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**So yeah. I apologize in advance for any not-up-to-date information on Gravity Falls, I have not had cable for over a year. (Keeping up with Phineas and Ferb only by purchase via iTunes). **


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